Thread: R380, transfer case and Diff synthetic oils

Haven't shifted into low range yet...yes I know I know not good enough

I wasnt gunna say anything!

I'm using Penrite Progear full synthetic 70-75 in the gearbox, and semi synthetic 80-90 in the TC & diffs.

My gearbox runs about 75 deg and the transfer case runs at about 65, on the freeway at 110 km/h, front diff runs high 40s rear diff mid 50s, oil filled wheel hubs mid 40s. Thats on a mild day last time I did the temperatures, say 30 deg ambient. Not towing, no roof rack, but reasonable load.

The highest temp is ambient plus 40. I asked penrite about those temps and was advised unless your getting up around the 100 deg C mark regularly or sustained, there's no need to fit a cooler.

It would good to hear from anyone who has temperatures for towing or big roofrack etc.

cheers simmo

We use Castrol Syntrans 75W85 fully synthetic in the TD5 gearbox and Gulf Western "Ultra Clear Gear Oil" 75W90 fully synthetic in the transfer. The gearbox oil is changed every 50k kms and the transfer every 20k kms (annually). We bought a 20l drum of each (getting down a bit) and service 3 vehicles, 2 TD5 Defenders and 1 TD5 Disco. Have been using these oils for years.

As an aside, Terry from Award Diffs (who knows a lot about these boxes) recommended a Royal Purple gear oil product, a few years back. This was quite expensive at the time.

Erich

Hi Topic Toaster,

Personally I use Royal Purple Fully Synthetic 75W-90 gear oil, have done successfully for many years now. Never had a problem. Gear and engine oils tend to be a personal choice on a lot of occasions based on personal experience. If you use a dealership as far as I am aware they align themselves with the best deal they can get for bulk oil supply unless you specifically request or you supply your own oil for them that is what you get.

The only oil choice I don't mess around with is the gearbox oil for the later models with the ZHP6 etc gearboxes installed., that I have found is very specific.

I just changed my gearbox & TC oils to Motul Gear 300 an I have to say, the synchros seem to like it better than the Penrite that was in there before. Shifting gears is definitely smoother than before.

Jbe was the Penrite the fully synthetic pro oil?

Cheers

On thing to bear in mind with manual trans fluids is that sometimes it can take up to 800km for the new friction modifiers to displace the old FM's and embed themselves into the synchro cone faces.

In other words don't do a fluid change and then think "this sucks"
It may take a day or two for the shift to improve.
I had this with one fluid I trialled, the first days upshifts crashed every single change, then it came good.